The invention relates to heat exchangers, for motor vehicles in particular.
It relates more particularly to a method of manufacturing a fin for a heat-exchange module which comprises at least two heat exchangers each including a body equipped with fluid-circulation tubes and moreover comprising cooling fins common to the exchangers, the fin consisting of a metal strip having a width divided into at least two heat-exchange regions by at least one series of longitudinal oblong holes spaced apart from one another.
There exist two principal technologies for producing heat exchangers for motor vehicles. According to a first technology, the constituent parts of the exchanger are assembled, then integrated in a single brazing operation. For this type of exchanger, the fins consist of corrugated spacers arranged between the tubes and parallel to them. According to another technology, the constituent parts of the exchanger are assembled exclusively by mechanical means such as crimping. This type of exchanger includes thin, flat fins arranged perpendicularly to the circulation tubes.
A motor vehicle generally includes several heat exchangers, for example a radiator for cooling the engine, a condenser forming part of an air-conditioning circuit and, if appropriate, a supercharging-air cooler or on oil cooler. It is advantageous to group these exchangers together into a single module which can be mounted in the vehicle in a single operation.
Such exchange modules then advantageously include common fins and are traversed by the same airflow. The fact that the fins are common to the various exchangers simplifies manufacture and makes it possible, furthermore, to make the assembly more compact.
Given that the various exchangers which constitute the module operate at different temperatures, it is necessary, in these common fins, to delimit heat-exchange regions specific to each exchanger. To that end, it is known to form series of oblong holes separated by narrow intervals of material so as to avoid thermal bridges between the various heat-exchange regions of the fin. According to the technique currently used, these oblong holes are produced by removing material, for example by perforation punching. This method has the drawback of generating scrap material which is difficult to manage in production and very expensive.
The precise subject of the invention is a method of manufacturing fins for a heat-exchange module including several exchangers which eliminates the production of scrap material.
This result is obtained, in accordance with the invention, by the fact that:
at least one series of longitudinal slits is formed, spaced apart from one another, in the metal strip; and
the longitudinal slits are widened so as to form a series of oblong holes spaced apart from one another.
By virtue of this method, the scrap material is eliminated, since the oblong holes are not obtained by removing material but by producing a slit which is then widened in order to constitute the oblong hole. That being so, the necessity of managing the scrap material is eliminated. Moreover, the fin can be produced from a metal strip of narrower width, which also leads to a reduction in its cost of manufacture.
According to a first variant of the method, stampings are formed between the longitudinal slits and these stampings are flattened so as to widen the slits and form the oblong holes.
According to another variant of the method, at least one series of slits is formed, distributed into two parallel rows spaced apart from one another in the direction of the width of the metal strip, and the metal strip is stretched in the direction of its width so as to widen the slits and form the oblong holes.
The slits of the two rows preferably overlap partially in the longitudinal direction of the metal strip.
The invention also relates to a fin for a heat-exchange module comprising at least two heat exchangers each including a body equipped with fluid-circulation tubes and moreover comprising cooling fins common to the exchangers. This fin is obtained by the method of the invention.
Finally, the invention relates to a heat-exchange module comprising at least two heat exchangers each including a body equipped with fluid-circulation tubes and moreover comprising cooling fins common to the exchangers. The fins are obtained by the method of the invention.